Magnetic switches with magnetically coupled armatures provide a compact, reliable and durable switching function. These switches offer a very slim profile, low weight, economical assembly, and are used in an increasing number of applications in a variety of environments. They combine the tactile feel of a bulky mechanical switch with the compactness of a conventional flexible membrane switch. Magnetically coupled switches of this general type are shown and described in U.S. Pat. Nos. 5,523,730, 5,666,096, 5,990,772, 6,069,552 and 6,262,646 the disclosures of which are hereby incorporated herein by reference. While switches with magnetically coupled armatures already have many applications, it is advantageous to expand the applications of such switches even further, and the present invention relates to a magnetic switch, suitable for a large variety of applications, with a dual armature that is normally magnetically coupled to a sheet magnet coupler layer in an un-actuated position. The dual armature, a substantially rectangular and flat piece of metal, has first and second free ends (usually the shorter sides of the rectangle) that oppose each other. If a user applied force acts on the first free end of the dual armature, then the first free end breaks away from the coupler magnet and travels into first electrical contacts that are normally spaced from the dual armature, and the second free end functions as a fulcrum for the dual armature. Conversely, if a user applied force acts on the second free end, then the second free end breaks away from the coupler magnet and travels into second electrical contacts that are normally spaced from the dual armature, and the first free end functions as a fulcrum for the dual armature.
There are numerous uses and needs for magnetic pushbutton switches of the type shown in U.S. Pat. Nos. 5,523,730, 5,666,096, 5,990,772, and 6,262,646. These magnetic pushbutton switches are characteristically designed to be momentary switches that momentarily affect the logic of external electronics connected to the switches. Once the applied actuation force of a user is released from the pushbutton switch armature of such magnetic switches, the switch armature does not remain in the actuated position, but is returned to its initial position by the magnetic attraction of a coupler magnet. In being returned to its initial rest position, with the armature held by the coupler magnet, there is typically a return of the logic of the external electronics connected to the switch to its initial state.
Frequently, switch applications will require two momentary pushbutton switches, each actuating an opposing function on the same electrical device. Examples of such switch applications include power window up/down switches and power door lock/unlock switches on an automobile. A problem encountered when using two pushbutton switches for these devices, whether they be magnetic, membrane or mechanical, is that individual pushbutton switches can be operated simultaneously even though they power opposing functions that should not be actuated simultaneously. One solution is to use springs to hold a mechanical rocking device that physically prevents both switches from being actuated simultaneously. The dual armature of the present invention utilizes fewer parts, uses no springs, and, in a preferred embodiment, prevents simultaneous actuation of opposing switches. Furthermore, the dual armature switch of the present invention is compact, provides a crisp tactile feel, and may be sealed to prevent dirt and moisture from entering the switch.
The magnetically coupled dual armature switch of the present invention includes a unique dual armature made of an electrically conductive and magnetic material and a sheet magnet coupler layer that magnetically attracts and normally holds the dual armature in a rest position The magnetic attraction also provides resistance to actuation, giving the switch a tactile feel, and provides a return force that returns the dual armature to its rest position after an actuation force is removed. The rest position is where the dual armature is held in coupled engagement with the sheet magnet coupler layer. The dual armature may travel into and/or out of shorting relationship with electrical conductors of the switch. Electrical leads connect the electrical conductors of the switch to electronics that may be external to the switch. The electrical conductors are arranged within the switch so that the electrically conductive magnetic dual armature of the switch is movable into and out of shorting relationship with the electrical conductors to change the circuit logic for a circuit incorporating the switch. As used herein, the term xe2x80x9cswitchxe2x80x9d includes devices for closing, opening, or changing the connections in an electrical circuit; the term xe2x80x9cmagnetic materialxe2x80x9d means a magnet or a material that is affected by a magnet; the term xe2x80x9celectrical conductorsxe2x80x9d includes electrodes, resistive elements, electrical wires, and spaced electrical contacts or pads; and the term xe2x80x9ctopxe2x80x9d refers to that surface of any part in a cross sectional figure of the drawings that faces the top edge of the page, while xe2x80x9cbottomxe2x80x9d refers to that surface that faces the bottom edge of the page.
The magnetic attraction between the sheet magnet coupler layer of the switch and the dual armature holds the top face of the dual armature in engagement with the bottom surface of the sheet magnet coupler layer. The dual armature of the magnetic dual switch of the present invention has at least two free ends that alternately function during switch actuation as either a fulcrum or to connect electrical contacts. An actuation force applied by a user to the top face of the dual armature substantially near one of the free ends of the dual armature causes the dual armature to pivot about the other free end that functions as a fulcrum. The top face of the dual armature breaks away from the sheet magnet coupler layer and travels into or out of electrical shorting relationship with electrical conductors of the switch. As the actuation force is applied by a user, the user feels a crisp, tactile snap as the top face of the dual armature breaks away from the sheet magnet coupler layer. When the actuation force exerted by the user is released, the dual armature is returned to and held in its rest position by the magnetic attraction of the sheet magnet coupler layer.
In a preferred embodiment of the magnetic dual switch of the present invention, the dual armature has a dual actuation barrier generally located substantially between the first and second free ends of the dual armature. In another preferred embodiment of the magnetic dual switch of the present invention, the edges that run perpendicular to the first and second free ends of the dual armature are third and fourth free ends that function as a second dual armature switch.